Musnad Ahmad 1153:1220

Abu ‘Asim narrated to us, Ibn Jurayj informed us, ‘Ata’ informed me, ‘Urwah ibn al-Zubayr informed me, he said: We were leaning against the chamber, and I was hearing the sound of the siwak, or her siwak, while she was brushing her teeth. I said: "O Abu ‘Abd al-Rahman, did the Messenger of Allah (peace and blessings of Allah be upon him) perform ‘Umrah in Rajab?" He said: "Yes." I said: "O Mother of the Believers, do you not hear what Abu ‘Abd al-Rahman is saying?" She said: "And what is Abu ‘Abd al-Rahman saying?" He said: "He says that the Messenger of Allah (peace and blessings of Allah be upon him) performed ‘Umrah in Rajab." She said: "May Allah forgive Abu ‘Abd al-Rahman. By Allah, the Messenger of Allah (peace and blessings of Allah be upon him) did not perform any ‘Umrah—or ‘Umrah—except that Abu ‘Abd al-Rahman was with him, and the Messenger of Allah (peace and blessings of Allah be upon him) did not perform ‘Umrah in Rajab."